The present invention relates to a dishwasher, particularly a domestic dishwasher, comprising a hot water inlet device for the intake of hot water from an external hot water supply, a cold water inlet device for the intake of cold water from an external cold water supply, and a program control device for controlling a wash cycle of a selected dishwashing program for cleaning food-soiled wash items.
In modern dishwashers, the wash items, in particular wash items requiring to be washed, are placed into a wash chamber and cleaned therein in a washing process, also designated a wash cycle, with the aid of water and are subsequently dried. The respective wash cycle can, in particular, comprise one or more partial wash cycles or wash cycle steps. The aim therein is to carry out a wash cycle such that a predefined cleaning result and a predefined drying result are achieved as efficiently as possible. A high degree of overall efficiency resulting from the cleaning efficiency and the drying efficiency is required. The cleaning efficiency corresponds to the ratio of the cleaning result achieved by means of a wash cycle to the effort required therefor, wherein the effort can involve several dimensions, such as energy usage, water usage and/or the time taken. Furthermore, the drying efficiency corresponds to the ratio of the drying result achieved by means a wash cycle to the effort required therefor, wherein here also the effort can involve several dimensions, such as the energy usage and/or the time taken.
Normally a program control device is provided in a dishwasher, wherein one or more wash programs, each for controlling at least one wash cycle for cleaning wash items, are stored. The program control device is embodied so as to control a wash cycle automatically in accordance with a program which is typically selected by a user. In known dishwashers, the water required for performing wash cycles can be fed in via a water inlet device which can take in water from a water supply installed in a building, for example.
In order to perform a wash cycle, a wash program preferably has a plurality of program steps in sequence for treating the wash items, the water being brought, in the program steps using water, to a temperature favorable for the respective program step, and provided with cleaning and/or additive substances depending on the respective program step. In order to be able to provide the water for washing with the cleaning and/or additive substances provided, modern dishwashers usually have automatic dosing devices. Dishwashers can also comprise a, typically electric, heating device to bring the water provided for washing to the required temperature.
For cleaning the wash items, a typical wash program comprises, in the following chronological order, in particular, a pre-wash step for performing a pre-wash cycle, a cleaning step for performing a cleaning cycle, an intermediate rinsing step for performing an intermediate rinsing cycle, and a final rinsing step for performing a final rinsing cycle in which the wash items have water or wash liquor solution applied to them. However, wash programs can also be provided in which one or more of these program steps are omitted. Wash programs are also possible wherein one or more of said program steps are repeated multiple times. Furthermore, a typical wash program comprises a drying cycle following on from the last partial wash cycle using water, said drying cycle being performed by a corresponding drying step of the selected dishwashing program, in order to dry the cleaned wash items.
A pre-wash step serves primarily to remove heavier soiling from the wash items. The purpose of a subsequent cleaning step is the complete removal of dirt from the wash items. An intermediate rinsing step serves, in particular, to remove cleaning agent residues adhering to the wash items. A subsequent final rinsing step is provided, in particular, to prevent spots that can occur on the wash items due to dissolved substances in the water, such as salt and/or lime. For this purpose rinse aid is added to the water during the final rinsing step.
In a dishwasher with integrated drying function, a further aim of the final rinsing step is to prepare for the subsequent drying step. For this, the wash items are heated to a high temperature during the final rinsing step.
In the subsequent drying step, water drops adhering to the hot wash items evaporate and condense on the inside of the wash chamber due to the lower temperature prevailing thereon.
DE 100 46 347 A1 discloses a water inlet device for domestic appliances such as a dishwasher which comprises a cold water valve and a hot water valve. Both the cold water valve and the hot water valve can be opened or closed by means of a control device depending on an operating program. Arranged downstream of the cold water valve and downstream of the hot water valve, in each case, is a water feed hose which ends in a branch connector. The sole outlet of the branch connector is connected to a water inlet fixed to the housing of the dishwasher. By this means the hot water needed by the dishwasher can be drawn from a hot water supply line, the water of which is heated by a domestic heating system.
DE 100 57 263 mentions a hot water supply for a domestic appliance which has solar collectors for hot water provision.
It is beyond question that the use of hot water from a domestic heating system can result in a saving of electrical energy, since in such a case the energy requirement of an electrical heater of the dishwasher can be reduced. Against the background of generally increasing operating costs of domestic heating systems, the additional costs incurred for operation of the domestic heating system that are associated with the drawing of hot water from the domestic hot water supply in many cases exceed the electricity cost saving.